Comparison of long-term ageing of binary Ag-Cu alloys

Silver alloys, due to its specific properties are widely used in different branches of industry, with approximately 95% of the world silver production is used in the photographic industry and for jeweller production. Moreover Poland is a significant producer of silver in the world, and takes the 6th place on the list of the world's silver producers with the KGHM Polish Copper Company production on the first place among global companies providing silver on the market, with an annual production at 1281 tones. Because of this impotent role of silver, this work presents microstructure and mechanical properties investigations results of the long aged Ag-Cu alloys used mainly for mint monetary production. The purpose of this work was to determine the microstructural changes after 32 and 40 year of natural ageing time, with appliance of transmission electron microscopy as well as light microscopy. A very important issue - one of the investigations directions is also the possibility of study of spinodal decomposition process, which occurred in this alloy. After the long-time ageing of the material, there are detected morphological different areas of the Ag-α and Cu-β phase. As an implication for appliance in real conditions - as coin metal, or in electronic and chemical industry branches, there is the possibility of application of long term ageing for mechanical properties improvement by natural ageing method. Some other investigations should be performed in the future, but the knowledge found in this research shows an interesting investigation direction, where a low cost but long term treatment operations can be applied.